Sheet post-processing apparatus

ABSTRACT

A sheet post-processing apparatus of the invention includes a sheet switch flapper which divides a sheet delivered from an entrance roller into an upper conveyance path and a lower conveyance path, an upper-surface sheet output tray provided in an end portion of the upper conveyance path, a lower-surface sheet output tray which is provided in an end portion of the lower conveyance path to stack the sheet thereon, the sheet being subjected to post-processing by a post-processing mechanism, a loading sensor which is provided in the upper-surface sheet output tray to detect that a predetermined number of sheets are stacked on the upper-surface sheet output tray, and a changeover mechanism which changes the sheet switch flapper to the lower conveyance path side at the time when the loading sensor detects that the predetermined number of sheets are stacked on the upper-surface sheet output tray.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2005-270515, filed Sep. 16, 2005, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet post-processing apparatus, such as a finisher, which is provided in a stage subsequent to multi function peripheral (MFP), and particularly to a sheet post-processing apparatus capable of smoothly stacking sheets to which post-processing is not performed.

2. Description of the Related Art

Conventionally there is known a finisher which binds up and staples plural sheets onto which printing is performed by MFP. In the finisher, the sheets delivered from the MFP are sequentially conveyed to a processing tray, and the sheets are bound by a stapler and discharged to a sheet output tray.

A delay mechanism for absorbing a processing speed at the MFP is required because the binding processing performed by the stapler exists in the post processing performed by the finisher. Therefore, a conveyance path is lengthened (for example, refer to Jpn. Pat. Appln. KOKOKU Publication No. 6-99070). For this reason, down-sizing of the apparatus cannot sufficiently be performed. There is also known a sheet output tray which is used only in not performing the staple processing (for example, refer to Jpn. Pat. Appln. KOKAI Publication No. 2000-53308).

There is the following problem in the conventional sheet post-processing apparatus. The finisher does not perform the processing to some of the sheets printed by the MFP. The sheets not subjected to such a processing are discharged to an upper-surface sheet output tray provided in an upper surface of the apparatus such that a user immediately takes out the sheets. In this case, when attempt is made to increase the number of sheets stackable on the upper-surface sheet output tray, the apparatus might be grown in size. For this reason, the number of sheets stackable on the upper-surface sheet output tray is limited to a predetermined number of sheets (for example, about 250 sheets).

BRIEF SUMMARY OF THE INVENTION

In view of the foregoing, an object of the present invention is to provide a sheet post-processing apparatus which can discharge sheets even if sheets to which post-processing is not performed are delivered in excess of the number of sheets stackable on an upper-surface sheet output tray.

In order to achieve the above object, a sheet post-processing apparatus according to one aspect of the present invention is configured as follows.

That is, the sheet post-processing apparatus comprises: an entrance roller which receives and conveys a sheet conveyed from an MFP main body; a sheet switch flapper which divides the sheet delivered from the entrance roller into an upper conveyance path and a lower conveyance path; an upper-surface sheet output tray which is provided in an end portion of the upper conveyance path to stack the sheet delivered from the entrance roller thereon when post-processing is not performed; a post-processing mechanism which is provided in the lower conveyance path to perform the post-processing to the sheet delivered from the entrance roller when the post-processing is performed; another tray which is provided in an end portion of the lower conveyance path to stack the sheet thereon, the sheet being subjected to the post-processing by the post-processing mechanism; an upper-surface sheet output tray loading sensor which is provided in the upper-surface sheet output tray to detect that a predetermined number of sheets are stacked on the upper-surface sheet output tray; and a changeover mechanism which changes the sheet switch flapper to the lower conveyance path side at the time when the upper-surface sheet output tray loading sensor detects that the predetermined number of sheets are stacked on the upper-surface sheet output tray.

According to the present invention, it is possible to discharge sheets even if sheets to which the post-processing is not performed are delivered in excess of the number of sheets stackable on the upper-surface sheet output tray.

Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.

FIG. 1 is a perspective view showing main parts of a post-processing apparatus of the invention;

FIG. 2 is a top view showing the main parts of the post-processing apparatus of the invention;

FIG. 3 is a view explaining an operation of a standby tray of the invention;

FIG. 4 is a view explaining vertical alignment and a sheet-bundle conveyance mechanism in the post-processing apparatus of the invention;

FIG. 5 is a view explaining a horizontal alignment mechanism of the post-processing apparatus of the invention;

FIG. 6 is a view explaining an operation of a stapler in the post-processing apparatus of the invention;

FIG. 7 is a side view showing the post-processing apparatus of the invention;

FIG. 8 is a perspective view showing a loading sensor of an upper-surface sheet output tray incorporated into the post-processing apparatus of the invention;

FIG. 9 is a perspective view showing the post-processing apparatus of the invention;

FIG. 10 is a view explaining a flow of a first sheet between an entrance roller and a sheet feed roller in the post-processing apparatus of the invention;

FIG. 11 is a view explaining the flow of the first sheet between the sheet feed roller and a standby tray in the post-processing apparatus of the invention;

FIG. 12 is a view explaining a flow of a second sheet between the sheet feed roller and the standby tray in the post-processing apparatus of the invention;

FIG. 13 is a view explaining an operation of a standby tray roller in the post-processing apparatus of the invention;

FIG. 14 is a view explaining the operation of the standby tray roller in the post-processing apparatus of the invention;

FIG. 15 is a view explaining an operation of active drop in the post-processing apparatus of the invention;

FIG. 16 is a view explaining a flow of a third sheet in the post-processing apparatus of the invention;

FIG. 17 is a view explaining the operation of the stapler in the post-processing apparatus of the invention;

FIG. 18 is a view explaining a flow of a sheet bundle between a processing tray and a sheet output tray in the post-processing apparatus of the invention; and

FIG. 19 is a view explaining a flow of direct sheet discharge to a third sheet output tray in the post-processing apparatus of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a perspective view showing main parts of a post-processing apparatus according to an embodiment of the present invention, and FIG. 2 is a top view showing the main parts of the post-processing apparatus of the embodiment. The main parts of the post-processing apparatus shown in FIGS. 1 and 2 include a standby tray 10, a processing tray 12, a stapler 14, a first sheet output tray 16, and a second sheet output tray 18.

A sheet 20 delivered from an MFP 1 is received by a pair of entrance rollers (entrance roller) 22, and then, a conveyance direction of the sheet 20 is switched between an upper conveyance path 74 and a lower conveyance path 80 by a sheet switch flapper 72 based on presence or absence of post-processing (refer to FIG. 7). In the case where the post-processing is performed, the sheet 20 is delivered to the lower conveyance path 80, and is then supplied to a pair of sheet feed rollers 24 and delivered from the sheet feed rollers 24 to the standby tray 10. On the other hand, in the case where the post-processing is not performed, the sheet 20 is delivered to the upper conveyance path 74, and is then supplied to a pair of upper-surface sheet discharge rollers 76 and delivered from the upper-surface sheet discharge rollers 76 to an upper-surface sheet output tray 70. The entrance roller 22 is driven by an entrance roller motor 26.

The entrance roller 22 includes an upper entrance roller 22 a and a lower entrance roller 22 b. Similarly, the sheet feed roller 24 includes an upper sheet feed roller and a lower sheet feed roller.

The standby tray 10 includes a pair of standby tray components 10 a and 10 b which is horizontally movable, and the sheet is received while the standby tray components 10 a and 10 b are closed. A standby tray roller 28 is provided to align the sheet in this state of things. The standby tray roller 28 is vertically movable, and the standby tray roller 28 is controlled by a standby tray roller drive source 30. A standby tray roller motor 32 rotates the standby tray roller 28.

When a predetermined number of sheets are accumulated in the standby tray 10, the standby tray components 10 a and 10 b are opened by a standby tray motor 34 as shown in FIG. 3, and the sheets 20 drop on the processing tray 12 by a self weight. This action is called active drop.

A paper path 36 is provided to guide the sheet delivered from the MFP 1 to the standby tray 10 and the processing tray 12, and a paper path ceiling is provided in the paper path 36.

Vertical alignment and horizontal alignment are applied to the sheet delivered to the processing tray 12. The vertical alignment is executed by a vertical alignment roller 38 as shown in FIG. 4. A vertical alignment upper roller 38 a is driven by a vertical alignment upper roller motor 40, a vertical alignment lower roller 38 b is driven by a vertical alignment lower roller motor 42, and the sheet is aligned based on a stopper 45. A paddle 44 is provided to assist the alignment, and the paddle 44 is driven by a paddle motor 46.

As shown in FIG. 5, the horizontal alignment is executed by a horizontal alignment mechanism 47 and a horizontal alignment motor 48.

When a predetermined number of sheets are accumulated in the processing tray 12, the stapler 14 performs the staple processing. As shown in FIG. 6, the stapler 14 is positioned to control the staple processing by a staple drive unit 49.

As shown in FIG. 4, a stapled sheet bundle is delivered to a sheet output tray (another tray) 16 or a sheet output tray (another tray) 18 by a conveyance mechanism 50. The sheet output trays 16 and 18 are selected by vertically moving the sheet output trays 16 and 18 with a sheet output tray drive unit 52.

FIG. 7 is a side view showing the post-processing apparatus of the invention. FIG. 8 is a perspective view showing a loading sensor 90 of an upper-surface sheet output tray incorporated into the post-processing apparatus of the invention. FIG. 9 is a perspective view showing the post-processing apparatus of the invention. An upper-surface sheet output tray 70 is provided in the post-processing apparatus. The upper-surface sheet output tray 70 is provided with the loading sensor 90 according to the number of sheets (for example, 250 sheets) stackable on the upper-surface sheet output tray 70. The loading sensor 90 includes an actuator 91 and a switch mechanism 92 such as a micro-switch. The actuator 91 is pressed by the stacked sheets 20 to be rotated about a rotating shaft 91 a. The switch mechanism 92 is turned on by the rotation of the actuator 91. A changeover mechanism 93 is provided to operate the sheet switch flapper 72 based on turn-on and turn-off of the switch mechanism 92. When the switch mechanism 92 is turned on, the changeover mechanism 93 changes the sheet switch flapper 72 from the side of the upper conveyance path 74 to the side of the lower conveyance path 80.

The sheet 20 is discharged to the upper-surface sheet output tray 70 through the entrance roller 22, the sheet switch flapper 72, the upper conveyance path 74, and the upper-surface sheet discharge roller 76.

In the sheet discharge utilizing the path, the sheet 20 is directly discharged not through the standby tray 10, the processing tray 12, and the stapler 14, so that sheet discharge speed can be enhanced.

When the post-processing is performed, a sheet bundle 21 is discharged to the first sheet output tray 16 or the second sheet output tray 18 through the entrance roller 22, the sheet switch flapper 72, the lower conveyance path 80, the sheet feed roller 24, the standby tray 10, the processing tray 12, and the stapler 14. A user can select and set the first sheet output tray 16 and the second sheet output tray 18. The sheet output tray to be used may be set in each section, or a user may individually be selected to set the sheet output trays 16 and 18.

An openable cover 78 can be provided on the upper-surface sheet output tray 70. In this case, when the openable cover 78 is locked, it is possible to manage a document which must not seen or taken out by others.

Obviously the openable cover 78 may not be provided. Therefore, throughput can be improved because the document to which the post-processing such as stapling is not performed can directly be discharged to the upper-surface sheet output tray 70 to shorten a conveyance distance.

An operation of the post-processing apparatus of the invention will be described with reference to FIGS. 10 to 18. As shown in FIG. 10, the sheet 20 delivered from the MFP 1 is delivered to the sheet feed roller 24 through the entrance roller 22.

Then, as shown in FIG. 11, the first sheet 20 is accumulated in the standby tray 10 through the sheet feed roller 24. At this point, the standby tray roller 28 is lowered as shown by an arrow, and the sheet 20 supplied to the standby tray 10 is aligned with a rear end (upstream side) 60 of the standby tray 10.

Then, as shown in FIG. 10, the standby tray roller 28 is lifted to prepare to accept a second sheet 20 a.

When the preparation is completed, the second sheet 20 a is delivered to the standby tray 10, and the standby tray roller 28 is lowered to align the positions of the sheets with the rear end 60 of the standby tray 10, as shown in FIG. 13. In this manner, a sheet bundle 20 b including the two sheets 20 and 20 a are formed in the standby tray 10.

Then, the standby tray roller 28 is lifted as shown in FIG. 14, and the standby tray components 10 a and 10 b are opened as shown in FIG. 3, which allows the active drop to be performed to deliver the sheet bundle 20 b to the processing tray 12 as shown in FIG. 15.

As shown in FIG. 16, a third sheet 20 c is directly delivered from the sheet feed roller 24 to the processing tray 12 without passing through the standby tray 10, and the third sheet 20 c is stacked on the second sheet bundle 20 b to form the sheet bundle 21 having a predetermined number of sheets. At this point, the vertical alignment mechanism 38 and the horizontal alignment mechanism 47 function to perform the vertical sheet alignment and horizontal sheet alignment.

At this point, as shown in FIG. 16, the rear end 60 of the standby tray 10 and a rear end 62 of the processing tray 12 are horizontally separated from each other by a distance L such that the rear end 60 of the standby tray 10 is located on the downstream side of the rear end (upstream side) 62 of the processing tray 12. According to the above configuration, the sheet bundle 20 b drops easily from the standby tray 10 to the processing tray 12, and the alignment operations can also easily be performed by the vertical alignment mechanism 38 and the horizontal alignment mechanism 47. As a result, the generation of jam can be prevented.

It is desirable that the standby tray 10 and the processing tray 12 be obliquely arranged while the upstream sides of the standby tray 10 and the processing tray 12 are inclined downward. That is, the standby tray 10 and the processing tray 12 are arranged such that the rear ends 60 and 62 are located in the lowest position, and the sheet 20 and the sheet bundle 21 can be aligned with the rear ends 60 and 62 by the self weight of the sheet 20 and the sheet bundle 21.

As shown in FIGS. 13 to 16, (1) the size of the standby tray 10 in the conveyance direction is smaller than the size of the sheet 20; (2) the size of processing tray 12 in the conveyance direction is smaller than the size of the sheet 20; and (3) when the sheet drops from the standby tray 10 to the processing tray 12 due to the relationship of the above (2), the sheet 20 is stacked while extending over the processing tray 12 and the sheet output tray 16. The size of the post-processing apparatus (finisher) in the conveyance direction can be decreased because these configurations (1) to (3) are adopted.

Then, as shown in FIG. 17, the stapler 14 staples the sheet bundle 21. As shown in FIG. 18, the conveyance mechanism 50 delivers the sheet bundle 21 to the sheet output tray 16, and the post-processing is ended.

In the case where the post-processing is not required, the sheet is, as shown in FIG. 19, directly discharged to the upper-surface sheet output tray 70 without passing through the standby tray 10 and the processing tray 12. As shown in FIG. 19, the sheet delivered from the MFP 1 is delivered to the upper-surface sheet output tray 70 through the entrance roller 22, the sheet switch flapper 72, the upper conveyance path 74, and the upper-surface sheet discharge roller 76.

When the number of sheets 20 stacked on the upper-surface sheet output tray 70 reaches a predetermined number, the actuator 91 is pressed and rotated by the stacked sheets 20, and the switch mechanism 92 abutting on the actuator 91 is turned on. When the switch mechanism 92 is turned on, the changeover mechanism 93 changes the sheet switch flapper 72 from the side of the upper conveyance path 74 to the side of the lower conveyance path 80. For this reason, the sheet switch flapper 72 is changed to the side of the lower conveyance path 80, and the sheet 20 is stacked on the sheet output tray 16 or the sheet output tray 18 through the lower conveyance path 80. Accordingly, even if the number of sheets 20 which do not require the post-processing exceeds the number of sheets stackable on the upper-surface sheet output tray 70, the sheets 20 can be held by the sheet output tray 16 or the sheet output tray 18.

As described above, according to the sheet post-processing apparatus of the embodiment, when the predetermined number of sheets are stacked on the upper-surface sheet output tray 70 to which the sheets 20 not subjected to the processing by the finisher are discharged among the sheets 20 printed by the MFP 1, the sheets 20 not subjected to the processing by the finisher are stacked on the sheet output tray 16 or 18. Consequently, the sheets 20 can be held even if the number of sheets 20 exceeds the number of sheets stackable on the upper-surface sheet output tray 70.

The above configuration is particularly effective in the case where a distance between the entrance roller 22 and the upper-surface sheet output tray 70 is sufficiently shorter than a distance between the entrance roller 22 and the sheet output tray 16 or 18 (for example, one-fifths), and the above configuration is more effective as the standby time or the post-processing time is lengthened.

The embodiment of the invention is described by way of example; but the invention is not limited to the embodiment. Each component shown in the embodiment can be changed to another component as long as the component has the same function.

Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 

1. A sheet post-processing apparatus comprising: an entrance roller which receives and conveys a sheet conveyed from an MFP main body; a sheet switch flapper which divides the sheet delivered from the entrance roller into an upper conveyance path and a lower conveyance path; an upper-surface sheet output tray which is provided in an end portion of the upper conveyance path to stack the sheet delivered from the entrance roller thereon when post-processing is not performed; a post-processing mechanism which is provided in the lower conveyance path to perform the post-processing to the sheet delivered from the entrance roller when the post-processing is performed; another tray which is provided in an end portion of the lower conveyance path to stack the sheet thereon, the sheet being subjected to the post-processing by the post-processing mechanism; an upper-surface sheet output tray loading sensor which is provided in the upper-surface sheet output tray to detect that a predetermined number of sheets are stacked on the upper-surface sheet output tray; and a changeover mechanism which changes the sheet switch flapper to the lower conveyance path side at the time when the upper-surface sheet output tray loading sensor detects that the predetermined number of sheets are stacked on the upper-surface sheet output tray.
 2. A sheet post-processing apparatus according to claim 1, wherein the lower conveyance path is formed longer than the upper conveyance path.
 3. A sheet post-processing apparatus according to claim 1, wherein a time in which the sheet passes through the lower conveyance path is longer than a time in which the sheet passes through the upper conveyance path.
 4. A sheet post-processing apparatus comprising: conveyance means for receiving and conveying a sheet conveyed from an MFP main body; sheet switch means for dividing the sheet delivered from the conveyance means into an upper conveyance path and a lower conveyance path; an upper-surface sheet output tray which is provided in an end portion of the upper conveyance path to stack the sheet delivered from the conveyance means thereon when post-processing is not performed; post-processing means provided in the lower conveyance path, the means performing the post-processing to the sheet delivered from the conveyance means when the post-processing is performed; another tray which is provided in an end portion of the lower conveyance path to stack the sheet thereon, the sheet being subjected to the post-processing by the post-processing means; upper-surface sheet output tray loading means provided in the upper-surface sheet output tray, the means detecting that a predetermined number of sheets are stacked on the upper-surface sheet output tray; and changeover means for changing the sheet switch means to the lower conveyance path side at the time when the upper-surface sheet output tray loading means detects that the predetermined number of sheets are stacked on the upper-surface sheet output tray.
 5. A sheet post-processing apparatus according to claim 4, wherein the lower conveyance path is formed longer than the upper conveyance path.
 6. A sheet post-processing apparatus according to claim 4, wherein a time in which the sheet passes through the lower conveyance path is longer than a time in which the sheet passes through the upper conveyance path.
 7. A sheet post-processing method comprising: receiving and conveying a sheet conveyed from an MFP main body; dividing the delivered sheet into an upper conveyance path and a lower conveyance path; stacking the delivered sheet at an end portion of an upper conveyance path when post-processing is not performed; performing the post-processing to the delivered sheet in the lower conveyance path when the post-processing is performed; stacking the sheet subjected to the post-processing on another tray at an end portion of the lower conveyance path; detecting that a predetermined number of sheets are stacked on the upper-surface sheet output tray with an upper-surface sheet output tray loading sensor provided in the upper-surface sheet output tray; and changing a sheet switch flapper to the lower conveyance path side at the time when the upper-surface sheet output tray loading sensor detects that the predetermined number of sheets are stacked on the upper-surface sheet output tray. 